where A corresponds to the carbon natural abundance,i.e.0.01108. (M0+1/M0)nat and (M0+2/M0)nat are the ratio of the integrated peak are as of m/z 61-to-m/z 60 and m/z 62-to-m/z 60 of acetate at natural abundance, respectively.
(M0+1/M0)sample and (M0+2/M0)sample are the ratio of the integrated peak are as of m/z 61-to-m/z 60 and m/z 62-to-m/z 60 of 13C enriched acetate samples, respectively.
Eqs. (2) and (3) are transformed to Eqs. (4) and (5) with two unknown variables for solving the TTR (M0+1) and TTR (M0+2), respectively. Using Eqs. (4) and(5), the solutions to TTR (M0+1) and TTR (M0+2) were given in Eqs. (6) and(7), respectively.